SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '689a607378be84be43d11579ca40c2260cf8c31c5eb6fb149b303247073e64a2' 
  AND token = 'n+A9RDvdphXtVqwL27JhXSFy9hSgku1h0flBCFYClbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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