SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727d0f89fe50114d293a08affe48cd89266db2c6a847eded5e8bacfeab12dde5' 
  AND token = 'iZmV12NvCqDIY5wPj+91NCichAlxBX9YFZw4Kw5fu34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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