SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8d1b4989828dbbaac09c89ac6f5218374975644a3aa32971852df990b1afaa68' 
  AND token = 'Rgetor2uAvmY+lOTXV/9KWb1w4EhJnOR5It4ClwjtlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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