SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8ad18b91695840f40a71b990f7593b6b524e36cffd58b180282398d59b0c7ee' 
  AND token = 'f5kuP7gzVPmo0PCTRpyQ7oqhnqr0jPAWTTGZjdKqaLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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