SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6a75f1ad3bf4faf28e7829f84fb558f41723308d61344e14aed75cdd8c09a59' 
  AND token = 'YCNc4h2jS4PFiKEVA3RqVIKPNiKgzmAlqlhQSh4d6HI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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