SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efd6403d5ac9e2a7d205e2c76183245b72a32dbaf6ac6965fdb9169e2c1b341c' 
  AND token = '9P19LUw2X3vBMQJgWKdTdHjzhf55VmJ4715+nQEZt+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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