SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77139a46540c2d41c028fa8131d153ee3308df0a4ee78b941cc2083f0c318888' 
  AND token = 'sOnIMPAp3HArwRrFYiwCSaiMoCmtUBKgraOtVS4a3Vw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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