SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '763dd38ff832e2f966a2229ae925847f83a82194dd8146ea1359aea03deb5c58' 
  AND token = 'U2U5vzm+7qzT0vGeszilTQSPwGqLMdGZ91S1Jj5z/Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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