SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f696628c92fda75f89cbd8aba04af502d0327ba18426c9fc0d5152c225b7f16' 
  AND token = 'synI5I42nnr5uYjyt8oLQy4eWPyOJZTDip3HtFSF83Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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