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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31e68fe54029dee99fc76a99ddf562489c89d043a9565ef6a1c26871a027a0ea' 
  AND token = '85mdARm8qknbnenMZABHapHabhxxaDd1SLWBlIhSl5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}