SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1e03aab16daf8b5ad2cc81c5b76d9de3a0c87eabcf4982200a7ebe68cd70068' 
  AND token = 'HWiN/y2vbLmvm8ZRKMvdL8v5lbCZlfsgminQadDaGiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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