SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a7a6f0c1deb2440532f3255716d2f94760489c5ec1f187f81dd0776e68402e4' 
  AND token = 'DupovqXcWKHxoyrYz/MjkZoMlwuadAkJUaGgs5/2IvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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