SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16f92720f1f801a97d3bf93dd3a0559f48607b430f1d13e8db9b5e19b5bc443d' 
  AND token = 'YTaMqDB2AVpllQ2BxImYCtxcG/VzM6p40DphyX1GugE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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