SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b51af1510b7fd91c70f7d5263e9806662ca945fecd61664684643e6582e9023d' 
  AND token = '+th/ht3SCQ4HPvYGY/kn8M9T/l2eR4NPOz8CBwsL/vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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