SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f952c28da986752e667944231fbbfcae926b9853cf55e121b48089607c82f24' 
  AND token = 'kc1q49D0rI88v5E0ICDMpyhxj0NeErWZxCVCdgCfKRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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