SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68caa7ef61a0cfd030cdb85927d1447df124bb07bc7c9aac322db52df9c134eb' 
  AND token = 'RRjRWv/GuWjpJCQ6CgFZuBmmYaR0C3ZLPTIksLRcgRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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