SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5719492be72ccfcfece657b5f28a563aecd1559a35c0fd059276de151ff1a294' 
  AND token = 'sS/MIAjYeUSnCsUitSAUxpsSFtcFEBwIldSMa3vAwS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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