SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4e06921862f5970b040c62d84db78713075e52fa6b9c46c406b5768de83973' 
  AND token = 'NTiurjiznAmMNmnSgXrWujDM30e+zvgmgF2kwC9WyDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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