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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fce0375909e1cd1810b403ad8ab2c4c9ecb7b3d47376ca56ce1db1ee867c8b39' 
  AND token = 'Ueg1YKDbFtft/bBqYa4sw6SwZIcRqo3KSWsBxdrGQr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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