SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2773eb327399253489c31c1f5cc1399fbf6dc9bfa56857604f5eba143774ea41' 
  AND token = 'dk/GuxMRjp8ctySe0WbZmwulUxz07MqtvEYFIMcMAYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}