SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424173c2c2df79f6c83c15a77b541460d639104b7f840ffa9777a878582aa4fb' 
  AND token = 'VWK3VrgHJcduODh+ldXeSDqgXjOKayBt2FzgPq7tMz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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