SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84575d5c2bc8c59fb5422f92fb08c9f1c3704d0ea2194ee663a68d476e5d3320' 
  AND token = 'At1POomdWGq4YZ/kV5ljUjQM3XBKulirlNOIt6EjvBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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