SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1375b4c11f900885903d972c37a45c413767e32858a1f760eec9aaf2ee20d261' 
  AND token = 'u8JrOmhJDTdwrvYUl0R1kBBB5MEkq/zywDg+H/Ty3jI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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