SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '357a135276d4b930f27c73725bcc977ebcefabdf72716c099aa89c3fd30ef493' 
  AND token = 'LTkGJvn21OYmCaB5FsoHhLU3/APrhWSm1WvWEowhiGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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