SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b428459f6bb781bbfaa092b39f383f87fa4bc54df2345489ceb1e9fb9aaa65ba' 
  AND token = '5wJCR/y6XjQ+nwUBAkGFVO6CmpxXKMniji0IiSFxnMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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