SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b83d9983b9cbb6c35b38e24b77046f1d495a4d0f66ea932293913d2c2e2ee49' 
  AND token = 'C2SAbS0vnFQJYiyABMmGmw+ol7sTNPKqmVyPdLhmhWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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