SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab899ff863a012b9b2c23a6c97c4de95a39333845d13016304fe543312bfeac6' 
  AND token = 'A95PJWuxJcJxXKSslZFl5CQkyaWWignsMsDyV+t7RJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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