SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c84847688251da9da36ae9a76aed1f69933e463e248b91e3fb107af3e4386cd' 
  AND token = 'NNb8uLKboUOJ7cARv6O83JPoiMv4iFqZk4jyjnQyUoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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