SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f40cb47f7fdb3efaab2a51d08b8b6a5991f29cb640c2be58d5ef948dddf1e81d' 
  AND token = '1gWUpOQhamvbfYfiZ5grUBJRfETMgt+wsLdrCagnRlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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