SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86946788823eda5c3b4dbb243d5492bf31fb537cef7546ae49247347c51f80e7' 
  AND token = 'RSf/ZHo3ek2NZruzgmLzdYwnjQI/gA+OXufmp3YRBkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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