SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b8608d2aa4b68ebf05476c1ac389b9511eed8983492692c382092f4b910d2f2' 
  AND token = 'MIIaxXXQJ7V4kF8gtJrOuUwdTkZaS1V9IEsX68KO1wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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