SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d2b335075ecc658b148a6f8f2ac08e535da1f0adcbc147136b2e9f998340fb2' 
  AND token = 'BPUusculQRaBvGURKUQLZPjzI3NGEGiSc1lq4MVE49s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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