SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e260ff4bff6522b2df35bfbf4849fb15fcbf0be7d2fd51260625ead97cc59cf2' 
  AND token = 'WkPinqb/S+fnoZh7HWqaOBg+cOIPtFKQHuFJUIzZXIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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