SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0ebbfa72077bfecf603cfdb7a4335b0bc38da0e582dc4674e01107436105984' 
  AND token = 'JKunQRqj2XC3H+VAs83yfpZLt1NCOrHDbKxgHeGfZJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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