SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e23eab594979fb1d45901b068804ef576707b6c81fe2d9ddc7abe60eece20a1b' 
  AND token = 'UCAnZzAycLt7lWMVTttNZ68uyHzhEcj4ijiwolH5FZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}