SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c593a3a1c2c720394751221c27f367bd749af5a1ee69d596723382804cb0efc0' 
  AND token = '6J54kj6CtKKdJK+5BNN9YJf/PFGpvnS3CgoM7382aLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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