SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe7333434e0478477a669a3b38351d274d98d0ba0f019ba210e0e8e7e15c571' 
  AND token = 'r/+Gzuh5HFZBmHDEE0AT+JLK1uLsKv1C0W5rNzPImgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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