SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3916dd72135a27b4b473ea7f9bc04695a0c744bc78ea0fa9064a5ad3bfd1774' 
  AND token = 'Le4RuvK3G/zPigI4PkFSBK/+sDjL3j5tVUkQAx4p+58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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