SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b995bbe39b1f84cf8900bb7dbf5bda7e4b3801d5b858812be54e85469108676' 
  AND token = 'zFiXQnrBUVkEesIEPj/u5zWro+bwxHU2sjlRERqiqmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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