SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '794760957a2bdd1d6a8a181d5de79fd76d67fa7b272433485e29951e144f5f77' 
  AND token = 'vVuXDT6+WHW66nPvpOCHzwpEKhMON/JJfMw5G3pmSNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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