SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2aeb95d092f3fb5986e40d36503284e626768dfb82792f9be61ecf4db9afdd31' 
  AND token = 'Kz5/LXzhZkMpB+0Ebv5SgpwpkpA+o5+3ZfRjIPtQE38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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