SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ae58c7ec32f33e89d378052328e0a3391a826581614e90b170d1a44d5f30364' 
  AND token = 'crF6dsg3P8qEGcTVjtmQB1AUYn1GUcVSy2pcfNXCntE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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