SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdf2c17a355187defec375616ff91dcd89893e9c2a65b42aaa94d51d8be570f4' 
  AND token = 'kQjjvT/QUTUYDW+vPgGVuzbfQhqVyNSDwscQIyW4cis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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