SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '343dce47b901fb1e28c15910ff27517c0a2668f34686b465c013ce9da24a74dc' 
  AND token = 'ZrcIAHYzEz3LyjBR03LDFUEiLHJ+9eiE6+wYupuoRH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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