SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a934bb22ffd8efde0822d047d2cdded9024680afae063fa1098c0028760c1404' 
  AND token = 'eNBSZpivPsl8qRGKj+dFxsxLzM6JS5TcjOwS27PAPiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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