SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef64ac814233a85ae5aa3aa0d0f1a22a1363fc8fbd992da2f34d9f2c89693c1' 
  AND token = 'Zj+M1iqnwU/EETYdCEquMg6nUGjvtQqJFvo2Vm7cOtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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