SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '491ae891dc3aaad18df337b5bd52e05eb0142cf497edf480a35e784e7388e6dc' 
  AND token = 'id0IPt5eewvn0NQXqUctfThAhHCBmCXKbFXourDJAh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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