SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3e8cbbca530657c7d16fa5a2ede4ec9c918ce00c1bc31ad4a5e5bc62cfd18ce2' 
  AND token = '3tLXhYcm5G4YHFj8W8k7QrfizxUWBquk7i1JWCxgNSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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