SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ef78c8661f17a83ecfa23846c0d1995a2fcf23dc44950613677c8f2452f2aa6' 
  AND token = '1Rb2mByJ+RKIzoIzwjXuCiRROdgRpq9xR9LireG0mKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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