SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c5193459b31bf512aa952c7f1dc2c53d1ea700890413b8b612267d5192f461' 
  AND token = 'U6q7Z/vOP9brs5O0tYUTZNEf+0nXJ2RkafATEu0ESQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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