SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '90b921d0b22883ef0563409a586ba110143036e410196d597e15169d9380a240' 
  AND token = 'gPwrJHQFq2vtCO/+gDnBrL3wlm6jJmZVjeDf154SOug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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