SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66556de4f3c326bcb9854cea3583254899aed10010c8804f21503eae9ba99cfb' 
  AND token = 'LY/8XjeLj083WnaQBN58ZE6Ae8goFVR2sEm3fKjapSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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