SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c92838793ac12f059a64dd461d0bb3a1a57df85d5b2b6fd2e18daeb5041f0669' 
  AND token = 'hhjEzkplGO/zDHxY2SsQHfGX45Nu/kT2aZdcB7wN8sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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