SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfe89e402dad3548fabbc64c196dd343ccfb50500dd4a1668b5ed35d8b8e09de' 
  AND token = 'GQ2NykE5ew9ItLRPhyCqL/beDxT5xizXkGBz15iTfVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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