SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '916f8420467d3ab58393d34ab9518bf9ed3d84045f4bfacca7a225a1faf36c51' 
  AND token = 'uV5/FlCLT9mWCFXUMuNG2UvVPDnEnwshKGkR81nL+Ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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