SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65b5b55bc399132704247f87518024040f5005df0859b6867e538d8b6a1e16d2' 
  AND token = 'pTF6A2K07E7FgvNR5WwiCe/UnjoPZVo17zogX+BL31Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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