SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504484e89df485fc28ea6781def6dfb84aa973a31502923f7d298e2f36aacccd' 
  AND token = '8CNhBNzRVI6zsWZoTZ2gbWeeEQuwDX2FWNrepgC6VmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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