SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8343246df3d52e2374405a3f7d574de7e43b468841c572936b3dd971070f3e0c' 
  AND token = '/jPPV1m3EeQXzo1Cs5BK/vGkwhUtvwwGpBEhvvnb3Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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