SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '798c2431b41e0fbc67b9b0488247744e1f1ade1d333d43c972c027685922e714' 
  AND token = 'cqxCCXK6PAI+usBSwT4rdLvsFX5OZvlSXM5L272ZMpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}