SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c59db569d8e83994db3079232f81f9e997d024679337f6cb8167d84510ab33' 
  AND token = 'Z6blK+4Wf78bw4BJDIL1IOjsx2Vvh/CIYloRwQQ7pYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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