SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '592ba850d4ecbcbee9eb765f57454c1140a49c1b6a69aa2cbdf1df3ee7a551d5' 
  AND token = '4w5zG7bpapUV/jXHFyFsi9q1hfgEFU6xRYuY0XzKZGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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