SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c540433de853a3d8902949e28a65f8b22aff5adda2eac15657ce665fc7aa4a1c' 
  AND token = 'Tb+7WVJ/lZSWWumVom3/orMH2cqpks77RuHoXrBjcfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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