SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '617e65bf4d125b663e23f089fd3475f3a28f64ff1255ad198a6fed5e9513a32e' 
  AND token = '5d/h/uFpH/u6LzTcR4AZjKfVRp8KgRqhROwJZAF3wEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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