SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a4dfed385c58425502b125558f3566ce035dfd2d7051a8c05cc34f19701a186' 
  AND token = '9vptQumFvIqGtBE8E9VSOz6CXHoMfdcGgTEJ2g2IKKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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