SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '902d1afaf468b1c41b7d7f289f5c9159bdec3cddae89523aedcdcf6a60fbb146' 
  AND token = 'At6xKo4FyuQlwsTHtOh6DgmJQh/6f++D8Q7cKbH2Prs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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