SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c67aef436dc7ab2a06132615bd3b7e848e2bc6527988aa2f34aae9213896834' 
  AND token = 'T+5womPJnlY66/bnwwFIHrsU0rMfncB5jzUSWuvFKMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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