SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76de0ea5e88d12491a398dd8d6d3a18745f211c9848fccbab6b48ca26c156122' 
  AND token = 'tU/XMZgCr231gjC/g/NskBk6sEArFgNfulySmNE9xTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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