SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c4f9d9ffcd3e2abba341cf83329e597be5670c59ecee52d2ae4def32a26559' 
  AND token = 'qrKdGBChDdLwhaossET7tFg9iRnManwRvaj4HOqqPJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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