SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e65c786cf77f1abc5c81c7578f906600a8a8b70859498e44b51daafe3abb99f6' 
  AND token = 'vmxhZusqtVK+QuUbHJFFRnD/YSMj/2+fZSGGz4jRRJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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