SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d6fdaa5413b87264a982b3015ccd06e8b252f7d09b794d234a2dd9935d7a965' 
  AND token = 'R8HMkHqVmPVDlTbcgK5HMxmx/tClN57xJaMGeMF1H8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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