SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75927429173c3cf6ba1359435a8ef48f0868658270886e3087c55147af43fe41' 
  AND token = 'OZS8b3EWxKuiGilEZcYflZYvB/p8+xVDovRH3CbrV/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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