SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bcbb68dbdca077aa0fc40153254e779f961335810de7b2755484f210a084ca4' 
  AND token = 'UNoFwFKDE+aQNoWYNULMnl59c2gwMt+4iuI0AJnCEi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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