SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89e51a8ae3e74cfddb7d484035fb40b94ff98579ee01a424a8103f6c8d257af2' 
  AND token = '2XLPrL2PqjyrD6oZWxd5D82IqW0fJHx0N3nUrOt2vDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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