SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcb6c0bdc14a98cc28f9728445ac54d9529ef488b2d828025827432b669f3fb2' 
  AND token = 'jLo45i+wb6iywGKyBJFRTSWdHxCvn+9fSZhQYqRt4sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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