SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4303f089e5919b316109958fd96ebce625b1173f6e3f7792944ca634e28d14c' 
  AND token = 'TJHdCdrMo+ayxxUiRZWG8+5UyewxOxoKobs7qoj5upo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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