SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15eed2e58176bdb4a736f02ebf32fbee8d8b8547f8f4ed71e36d88baf1c0f6d' 
  AND token = 'jfhuDyJ2wYPu2Khq223LJC/Han1GfYxx3jvLATgtxi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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