SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85d3a523c583b87853c339ee01a32d29781060304f509826f979605b09dc6c5d' 
  AND token = 'jkaIL/9RN1RTTg17WAQDfevwKJohRN54PhhUnCnzGuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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