SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f230badb602a85e1eea179aa79ae331df51ba2b4c50434b641ee582c09050c2b' 
  AND token = 'T49MDhFnq5DxAwFwn1uMHwGBkyRrDQKZBRl2glLlhsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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