SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20151ece2ce192145a97cecd35751f76171ad8084eb78366f351b4dda267ea72' 
  AND token = 'I/B6MlfHObGWWUqsCU37c/w/+AoJx2bhGlX8f9lVYVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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