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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91fb59ab843a9313ec91e262aaafe3da7bf84cc334472762b4570e6be643df3' 
  AND token = '87+AU/HlEpG/eLagyz8+b7EkVzMS96+VaSgHK2TRy3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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