SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e635c938c34b9516afde2e27a6aff962bb4c0d1846a9b623823b8dc86924498' 
  AND token = 'vyl6nb3Q9pd4QPJKHw/pFEQy+utFdcHytrLADL9XEa0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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