SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3890a372ed946bdb54e151af2967b762056cce02f718d657319434a1fbd01eec' 
  AND token = 'QRy03QLz0NAVaJoANTjcPlmQSehi5JeCNBghLnIiIic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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