SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3cb5418cf1c59404944db3ba473bb728c90d348b5a5e409425b568f33e0d99f' 
  AND token = 'BD16zHzvz0Jv8FK+HQCo+gwUZOkCw/D1ZrlHnJ3oi7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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