SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edc3a42c5215bf7ba44ec3b3bcf4e7bdf438442c5162be672301184293d4832d' 
  AND token = 'zllkXsYhYqmoa1BBu3LAuK5rYJOAMPXWA/yEpZ+Ldpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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