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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76348c8e42752ce70d08d3f9488afced770943408db6a31782257a4adf2f029c' 
  AND token = 'pyrcPFTDtBKVe/ES51A0omvR03kqhjvzbsb7rjs+a04=' 
  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"
    }
  }
}