SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8abc06693035dd476dbbfbba881466700b4cd6f7408a20393bb084faaaa1cbb1' 
  AND token = 'P7jdLECla7qrwMug/UKil5YnSI2trckjiE64n4+vnLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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