SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '519e84f3164a7a95c31f59177b37cbfd4b83a7723f7bbca987211444c12f7d6c' 
  AND token = 'XqsZJo/LY6mOkQNhWBFl0xUtevSCSd0Yz6hzikZ1oT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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