SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26b68d8f9db909c66d5d74515249928c442c5edae7b167da88aa5014df0faa30' 
  AND token = 'Zv2wAUqet6xaTFSDHq4xCX3JxFIdj1DdHfafR88OWB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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