SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d3820d505e1bfd8332c1e5f31d714a06e3da7689bdfe27a3345a26369fb4834' 
  AND token = 'Gmq5FwVAS9UO+nnPh7kWvPIlguOzbQLdi8LGUaReeMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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