SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31cb1dc1f863ed72a8d326148d08691cd28abcff09e04656d4ea0c5797816360' 
  AND token = 'hpQSq8M2PDKq3psmGjHdmmunzeuWSjkz9JutPAIY83o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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