SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed542e8d9435442e5319d0bdff49901479fd0ff1cc024cca9cdcf73052e4b6ca' 
  AND token = '4HeqDmAPaIA+lH9JnqZAYyncKkYNKOW2qWLneSRFfWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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