SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd336cb155f60a7383c4afd85deb8ca92ad5eb4c7202386e116207b31edddb517' 
  AND token = 'aPpumci+W9+lcn9eZC3qQwjNyMScYB/4+rDPhGijV/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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