SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9468e6611eb917778d8040f8a60d5947065ac16c2b1e6fe301d9aa9c3ddf91' 
  AND token = 't7myOgC1z/XqwJYDGR5wgb7gKOC7DjQCQCSj2vhH3sY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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