SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '556e52d6559715624976e02177c8d1b0926e88bad4ffc9e102d347eeafc9e1c1' 
  AND token = 'bK2ghkxuQXK7WLzhbP15GLsjYyKmbH3/YkiLXZyMwAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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