SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b0bfe1d0b7ea04f61116036cdcf03acf917bc327ede25d1b354c9e352f328f6a' 
  AND token = 'cP4phFwRgSrf4phJO20olf9ACdeoZknFV/YuAZ49rCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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