SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcdc56eea46a65ca953d8e1b91a49845b26e1a187816bc554d949d3cbd5c27c6' 
  AND token = '39BLRBSGOS1vjMtl5dsmWkwYLOYYu6m04utPCRPrlrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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