SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14a18eb1032e1901f763722537c18732876380e72dd6141db41287a8110cf9cc' 
  AND token = 'auFcklfFEH+cr/dmcpFMqC8KMvoYZMIiAqdOsDChAO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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