SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52f5b943d96e55fcf58dcdf54f784b2eb1288802cb680423a8337a3e4f043be9' 
  AND token = 'zP78hEVqZ/D6HpbyxjRZNY0AqT9CNweBsA+PikGAh/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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