SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5af9ff1eab0a8f1064a9bc6d79e34f6346102d2d757ba1449f2e1c15ac124b3c' 
  AND token = 'ik8VMwB+jf7MVp5F+LoDFZn0GOmnSPy5llR9W6GyChQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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