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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e71f595ecd11a520af37d587ee0c9f324d94a46c8dfa7333f08c26f109f39ab2' 
  AND token = 'B/IZtLLPxJ1uMkuV7Iswz+w/0RQADSo2fWktjQ1tC5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}