SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dfaa3451894e40d010257e54a4951a762bca53eec422fb0403247a79cb32478' 
  AND token = 'HMHJE5rgdCpiTmooE2J18KeFqcpkgOm69uTIqOoheAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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