SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '01a355fd76f700dd0598775da1a305f9148c32ff4441382e38f1a0ddc4db34fe' 
  AND token = 'klN9+sgNwUvhX/JNVcWkvprWJ3uy/zfsq7lzPhFPGg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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