SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e1bc9feba819e3a9fa8479d8724c0b20ab86ca1414e729b0f975c25a6a3a936' 
  AND token = '2jWqW3Z7N+b6UjkPefPNqiS+HqRcBJHgUAcWnGnyy1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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